Carrier frequency of GJB2 gene mutations c.35delG, c.235delC and c.167delT among the populations of Eurasia.

Hearing impairment is one of the most common disorders of sensorineural function and the incidence of profound prelingual deafness is about 1 per 1000 at birth. GJB2 gene mutations make the largest contribution to hereditary hearing impairment. The spectrum and prevalence of some GJB2 mutations are known to be dependent on the ethnic origin of the population. This study presents data on the carrier frequencies of major GJB2 mutations, c.35delG, c.167delT and c.235delC, among 2308 healthy persons from 18 various populations of Eurasia: Russians, Bashkirs, Tatars, Chuvashes, Udmurts, Komi-Permyaks and Mordvins (Volga-Ural region of Russia); Belarusians and Ukrainians (East Europe); Abkhazians, Avars, Cherkessians and Ingushes (Caucasus); Kazakhs, Uighurs and Uzbeks (Central Asia); and Yakuts and Altaians (Siberia). The data on c.35delG and c.235delC mutation prevalence in the studied ethnic groups can be used to investigate the prospective founder effect in the origin and prevalence of these mutations in Eurasia and consequently in populations around the world.

A counter-clockwise northern route of the Y-chromosome haplogroup N from Southeast Asia towards Europe.

A large part of Y chromosome lineages in East European and East Asian human populations belong to haplogroup (hg) NO, which is composed of two sister clades N-M231 and O-M175. The O-clade is relatively old (around 30 thousand years (ky)) and encompasses the vast majority of east and Southeast Asian male lineages, as well as significant proportion of those in Oceanian males. On the other hand, our detailed analysis of hg N suggests that its high frequency in east Europe is due to its more recent expansion westward on a counter-clock northern route from inner Asia/southern Siberia, approximately 12-14 ky ago. The widespread presence of hg N in Siberia, together with its absence in Native Americans, implies its spread happened after the founder event for the Americas. The most frequent subclade N3, arose probably in the region of present day China, and subsequently experienced serial bottlenecks in Siberia and secondary expansions in eastern Europe. Another branch, N2, forms two distinctive subclusters of STR haplotypes, Asian (N2-A) and European (N2-E), the latter now mostly distributed in Finno-Ugric and related populations. These phylogeographic patterns provide evidence consistent with male-mediated counter-clockwise late Pleistocene-Holocene migratory trajectories toward Northwestern Europe from an ancestral East Asian source of Paleolithic heritage.